The business case will form part of the county's application for government funding under the next round of private finance initiative bids.
Turner & Townsend is a firm of project management specialists with transportation expertise, while Arthur Andersen will provide the financial analysis within the business plan.
Their bid beat strong applications from Ernst & Young, Deloitte Touche, KPMG, Mouchel/ Deloitte Touche, PricewaterhouseCoopers and Value Management Ltd.
If approved, the scheme is likely to provoke substantial interest from private sector construction and transportation specialists.
Hertfordshire is keen to develop a guided light tram or trolley bus service, providing the quality of a light railway system without the expense. It also wants a design flexible enough to be run on its existing road network.
At this stage project costs are estimated to be in the region of£80 million.
Brian York, Hertfordshire's Labour environment committee chairman, said he was pleased with the response from the consultants: 'It is pleasing to record the fact that private companies are willing to respond and show an interest in the project. This is obviously helpful to the public/private partnership programme and the PFI process itself.'
Liberal Democrat vice-chairman Michael Moore said: 'We all hope that when we submit our CHPTS outline business case in March next year it will receive similar approval to that recently announced for the Nottingham Transit System.
'If is approved we will be seeking private sector partners for a consortium that would possibly build and operate this much-needed system.'